Armor system for vehicles (such as military vehicles and the like) are generally known and may include an armored skin material (such as ceramic tiles) covering the vehicle. The type of armored vehicle skin typically used to provide protection to the occupants and operating systems of a vehicle may be classified on certain established criteria, such as “probability of kill” (Pk) criteria. Statistically, even a modest level of armor protection greater than a basic vehicular “soft body” can be shown to reduce (Pk), with a more significant reduction in (Pk) for most battlefield scenarios once protection from low energy threats such as blast fragmentation or light arms fire has been achieved. As armor protection level is increased, the (Pk) further reduces, but usually at the expense of disproportional increases in vehicle weight and manufacturing cost. Accordingly, it would be advantageous to advance the technology of lightweight, low cost armor solutions for vehicles.
Generally, the threat type that vehicle armor protection may encounter might first be classified as either blast or projectile (although most threats combine both to some lesser or greater extent). For example, artillery rounds, some mines, rocket propelled grenades (RPGs) and improvised explosive devices (IEDs) often combine both effects.
Blast type threats may be considered largely as a “pressure effect”, and the armored skin materials and thickness considered necessary to protect occupants and vehicle systems is not only dependent on the size of the blast, but also on the distance from the blast and the portion of the blast actually reacted by the vehicle. In other words; the shape, size and orientation of the surfaces exposed to the blast wave are factors for consideration in designing an effective vehicle armor system.
In general, the occupants of “light” vehicles are inherently more vulnerable to blast than in a “heavy” armored vehicle because a given blast intensity will tend to impose greater accelerations on a lighter mass than a heavier one. In this respect, for a given blast survival capability for a minimum vehicle weight, consideration is given to mitigating the effects of blast accelerations on the vehicle occupants. Such considerations usually are based upon human medical factors including methods of reducing the occupants' spinal loading in mine type (e.g. below-ground) blast events, as well as methods of reducing, longitudinal and lateral accelerations and consequential impact of the occupants within the vehicle's internal structure caused by both a mine blast event and above-ground blast events. Information from helicopter seat design and automobile crash testing, including side crash tests, have shown that the human medical factors approach in design tends to improve occupant survivability. Accordingly, the lessons learned and techniques developed in automotive crash design; e.g., occupant restraint and air-bag protection, may well be applicable to designing armor systems for survival of light military vehicles from above-ground and below ground blast events.
Generally, for a design that minimizes occupant injury during a blast event, the vehicle's armor skin thickness should withstand any blast event up to the limit of occupant survival. Beyond that, structural redundancy, if not beneficial to projectile protection, tends to result in excess weight and degradation of such otherwise desirable parameters as vehicle acceleration, grade capability, handling, roll-stability, payload capacity, fuel efficiency, transportability and mobility.
Design of an armor system for a vehicle that is capable of withstanding projectile threats tends to present a different set of challenges and covers a wide spectrum of possible threats where the effects of the projectile are intended to concentrate their energy on a very localized area of the armor to breach the armor's protection. Projectile threats are typically grouped as kinetic energy projectile or chemical energy projectile types.
Both kinetic and chemical energy projectile types typically use the physical properties of mass and velocity to impart a high level of energy to a small area. Certain kinetic projectiles use the velocity of the projectile to the target (for example, typically within a range of 700 to 4,500 miles per hour (mph)), and certain chemical projectiles use an explosive chemical energy charge to reshape a metal billet into a higher velocity (for example, about 15,000 mph) projectile in the form of a solid jet or slug of metal.
Kinetic projectiles types typically range from small fragments and bullets (at a lower end of the scale) through specialized armor piercing bullets and may include substantial depleted uranium penetrator rods (at an upper end of the scale).
Since the more advanced chemical and kinetic projectiles typically in use lately are often capable of breaching hardened steel plate having a thickness of a foot or more, it is generally considered impractical for any vehicle, even the heaviest and most advanced battle tank, to be effectively armored “against all threats”. Thus, a threat/force protection strategy for any vehicle type is usually a compromise between detectability (e.g. stealth), armor protection, and mobility; with mobility often influencing survivability and typically degrading with increased vehicle weight (i.e. increasing levels of conventional armor protection).
Accordingly, it would be desirable to provide a lightweight vehicle armor system that is capable of providing a desired level of occupant and vehicle system survivability protection for both blast and projectile type threats. It would also be desirable to provide a lightweight vehicle armor system includes a lightweight high tensile aluminum alloy body panel of the vehicle combined with a thin, boronized, case-hardened steel tiles with a dense particle-filled elastomer provided therebetween to spread local impact loads and dissipate some of the impact energy laterally. It would be desirable to provide a lightweight vehicle armor system that is intended to provide the advantage of being relatively inexpensive compared with conventional ceramic tile laminate armor systems, while being lightweight when compared with conventional hardened steel solutions. It would be desirable to provide a lightweight vehicle armor system that is readily adaptable for use with vehicle body panels having a stressed skin construction.
Accordingly, it would be desirable to provide a lightweight vehicle armor system having any one or more of these or other desirable features.